Apparatus for producing spark ignition of an internal combustion engine

Claim 2

Apparatus for producing spark ignition of an internal combustion engine wherein combustion is effected by means of a spark plug in a cylinder of an engine, said apparatus comprising: spark pulse generating means for applying to the spark plug an electrical pulse capable of initiating a spark across the spark plug; and a d.c. to d.c. converter capable of producing a continuous output voltage for application to the spark plug to sustain sparks established by said spark pulse generating means, said converter being adapted to produce substantially constant voltage over a predetermined range of current values supplied by the converter to sustain the spark, said converter being arranged to substantially cease operation in the event that the current supplied by the converter exceeds a predetermined maximum value.

Claim 3

Apparatus as claimed in claim 1 wherein said d.c. to d.c. converter comprises: a) a step up transformer having a primary a secondary and a feedback winding, and a saturable core b) semiconductor switching means coupled to said primary winding and to said feedback winding so as to define an oscillator to produce an oscillatory current flow in said primary winding that saturates said core with magnetic flux whereby to induce an oscillatory stepped up voltage in said transformer secondary winding c) rectifying means coupled to said transformer secondary winding and arranged to produce a rectified output voltage for application to the spark plug, and d) the converter being so arranged that in the event said output voltage is shorted to earth the oscillator becomes damped and substantially ceases operation.

Claim 4

An internal combustion engine provided with a spark ignition system wherein combustion is effected by means of a spark plug in a combustion chamber of the engine, comprising: a) an ignition coil having primary and secondary windings the output of the secondary winding being arranged to supply high voltage pulses to the spark plug b) a relatively low voltage supply c) means responsive to said low voltage supply and arranged to produce in said primary winding a rate of change of current for inducing in said secondary winding voltage pulses suitable for initiating a spark at said spark plug, and d) a d.c. to d.c. converter capable of producing a continuous output voltage for application to the spark plug to sustain a spark established by one of said voltage pulses when the pulse is no longer capable of maintaining the spark, said converter comprising: a step up transformer having a primary a secondary and a feedba.ck winding, and a saturable core; semiconductor switching means coupled to said primary winding and to said feedback winding so as to define an oscillator to produce an oscillatory current flow in said primary winding that saturates said core with magnetic flux whereby to induce an oscillatory stepped up voltage in said transformer secondary winding; rectifying means coupled to said transformer secondary winding and arranged to produce a rectified output voltage for application to the spark plug; and the converter being so arranged that in the event said output voltage is shorted to earth the oscillator becomes damped and ceases operation.

Claim 5

An internal combustion engine provided with a spark ignition system wherein combustion is effected by means of a spark plug in a combustion chamber of the engine, comprising: a) an ignition coil having primary and secondary windings the output of the secondary winding being arranged to supply high voltage pulses to the spark plug b) a relatively low voltage supply c) means responsive to said low voltage supply and arranged to produce in said primary winding a rate of change of current for inducing in said secondary winding voltage pulses suitable for initiating a spark at said spark plug, and d) a d.c. to d.c. converter capable of producing a continuous output voltage for application to the spark plug to sustain a spark established by one of said voltage pulses when the pulse is no longer capable of maintaining the spark, said converter comprising: a step up transformer having a primary a secondary and a feedba.ck winding, and a saturable core; semiconductor switching means coupled to said primary winding and to said feedback winding so as to define an oscillator to produce an oscillatory current flow in said primary winding that saturates said core with magnetic flux whereby to induce an oscillatory stepped up voltage in said transformer secondary winding; rectifying means coupled to said transformer secondary winding and arranged to produce a rectified output voltage for application to the spark plug; and the converter being so arranged that in the event said output voltage is shorted to earth the oscillator becomes damped and ceases operation.

Claim 6

An arrangement as claimed in claim 3 including a voltage multiplier stage connected to the output winding of the transformer, to produce a rectified multiple of the oscillatory voltage developed across the output winding, an output capacitor arranged to be charged as a function of said rectified multiple voltage produced by the voltage multiplier stage, and resistor elements connected in parallel with said output capacitor to provide therefor a discharge path when the converter is inoperative.

Claim 7

An arrangement as claimed in claim 4, including function indicator means to indicate that said converter is operative.

Claim 8

An arrangement as claimed in claim 5 wherein said function indicator means comprises a neon tube connected in parallel with said output capacitor.

Claim 9

An arrangement as claimed in claim 3 including sensor means for providing an output indicative of an engine operating parameter, and means responsive to the output of the sensor means and arranged to control the magnitude of the output of said d.c. to d.c. converter such as to minimise spark erosion of the spark plug.

Claim 10

An arrangement as claimed in claimed in claim 3 wherein a separate inductor coil is connected in series with and between the output of said d.c. to d.c. converter and the secondary winding of said ignition coil, a spark plug output for connection to the spark plugs is taken at the series connection of said separate coil and said secondary winding of the ignition coil, and voltage isolating means is provided to permit said high voltage pulses induced in the secondary winding to pass to said spark plug output, said voltage isolating means also being adapted to cause current from the d.c. to d.c. converter to flow to said spark plug output rather than through said secondary winding of the ignition coil.

Claim 11

An arrangement as claimed in claim 8 wherein said ignition coil has four terminals each of which is connected to a respective end of said primary and secondary windings, and wherein one terminal of the secondary winding is connected to earth through said voltage isolating means.

Claim 12

An arrangement as claimed in claim 8 wherein said ignition coil has three terminals, a first and a second of which are connected to respective ends of said primary and secondary coil windings, the third terminal being connected in common to the other two ends of said windings, said third terminal being earthed, and said voltage isolating means is connected to said second terminal and to said spark plug output,

Claim 13

An arrangement as claimed in claim 8 wherein said voltage isolating means comprises electrodes defining a spark gap.

Claim 14

An arrangement as claimed in claim 8 wherein said voltage isolating means comprises a diode.

Claim 15

An arrangement as claimed in claim 8 wherein said voltage isolating means comprises a capacitor.

Claim 16

An internal combustion engine including a) a combustion chamber; b) a spark plug for producing spark ignition in said chamber; c) spark pulse generating means for applying electrical pulses to the spark plug in a timed relationship dependent upon operation of the engine, said pulses being capable of initiating sparks across the spark plug; d) generator means capable of producing a continuous output voltage for application to the spark plug so as to sustain the spark established by the spark pulse generating means after the pulse generated thereby is no longer capable of maintaining the spark; e) sensor means for providing an output indicative of an operating parameter of the engine; f) means responsive to said output of the sensor means and arranged to control the magnitude of the output voltage of said generator means in such a manner as to tend to minimise spark erosion of said spark plug.

Claim 17

An internal combustion engine including a) a combustion chamber; b) a spark plug for producing spark ignition in said chamber; c) spark pulse generating means for applying electrical pulses to the spark plug in a timed relationship dependent upon operation of the engine, said pulses being capable of initiating sparks across the spark plug; d) generator means capable of producing a continuous output voltage for application to the spark plug so as to sustain the spark established by the spark pulse generating means after the pulse generated thereby is no longer capable of maintaining the spark; e) sensor means for providing an output indicative of an operating parameter of the engine; f) means responsive to said output of the sensor means and arranged to control the magnitude of the output voltage of said generator means in such a manner as to tend to minimise spark erosion of said spark plug.

Claim 18

An engine as claimed in claim 14 including an EGR system and wherein said sensor means includes means responsive to the EGR rate of the engine.

Claim 19

An engine as claimed in claim 14 or 15 wherein said sensor is responsive to the strength of fuel mixture supplied to the engine.

Claim 20

An engine as claimed in claim 14, 15 or 16 wherein said sensor means is responsive to engine temperature..

Claim 21

An engine as claimed in claim 14 including a relatively low voltage supply, and wherein said generator means comprises a d.c. to d.c. converter including, a step up transformer having a primary and a secondary winding, semiconductor switching means coupled to the primary winding of the transformer so as to switch current from said low voltage supply and produce an oscillatory current flow in said transformer primary winding thereby to induce an oscillatory high voltage in the transformer secondary winding, and rectifying means coupled to transformer secondary winding and arranged to produce a relatively high rectified output voltage for application to the spark plug, and including a voltage dropping impedance means arranged to reduce the voltage produced by said d.c. to d.c. converter, and switching means responsive to said sensor means to disable operation of said voltage dropping impedance means.

Claim 22

19 . An engine as claimed in claim 18 wherein said switching means comprises a relay having a coil and switching contacts, said relay coil being energised from said low voltage supply in dependence upon operation of said sensor means, and said voltage dropping means beingshunted by said switching contacts.

Claim 23

An engine as claimed in claim 19 wherein said voltage dropping impedance means comprises a resistor connected to reduce the low voltage supply received by the converter.

Claim 24

An engine as claimed in claim 19 wherein said voltage dropping impedance means comprises a resistor connected to reduce the high output voltage produced by the d.c. to d.c. converter.

Claim 25

Apparatus for producing spark ignition of an internal combustion engine wherein combustion is effected by means

Claim 26

Apparatus for producing spark ignition of an internal combustion engine wherein combustion is effected by means

Claim 27

of a spark plug in a combustion chamber of the engine, comprising: spark pulse generating means for applying repetitively to the spark plug an electrical pulse capable of initiating a spark across the spark plug; a d.c. to d.c. converter capable of producing a continuous output voltage for application to the spark plug to sustain a spark established by the spark pulse generating means after each spark initiating pulse therefrom is no longer capable of maintianing the spark, said converter comprising: a) a step up transformer having primary secondary and feedback windings, and a saturable core b) semiconductor switching means coupled to said primary winding and to said feedback winding in such a manner as to define an oscillator to produce an oscillatory current flow in said primary winding which produces a magnetic field that saturates said core whereby to induce an oscillatory stepped up voltage in said secondary winding; c) rectifying means coupled to said secondary winding and arranged to produce a rectified output voltage for application to the spark plugs; d) the converter being so arranged that in the event of short circuit of said output voltage to earth said oscillator becomes damped and ceases operation.

Claim 28

of a spark plug in a combustion chamber of the engine, comprising: spark pulse generating means for applying repetitively to the spark plug an electrical pulse capable of initiating a spark across the spark plug; a d.c. to d.c. converter capable of producing a continuous output voltage for application to the spark plug to sustain a spark established by the spark pulse generating means after each spark initiating pulse therefrom is no longer capable of maintianing the spark, said converter comprising: a) a step up transformer having primary secondary and feedback windings, and a saturable core b) semiconductor switching means coupled to said primary winding and to said feedback winding in such a manner as to define an oscillator to produce an oscillatory current flow in said primary winding which produces a magnetic field that saturates said core whereby to induce an oscillatory stepped up voltage in said secondary winding; c) rectifying means coupled to said secondary winding and arranged to produce a rectified output voltage for application to the spark plugs; d) the converter being so arranged that in the event of short circuit of said output voltage to earth said oscillator becomes damped and ceases operation.

Claim 29

Apparatus for producing spark ignition of an internal combustion engine wherein combustion is effected by means of a spark plug in a combustion chamber of the engine, comprising: spark pulse generating means for applying repetitively to the spark plug an electrical pulse capable of initiating a spark across the spark plug and a d.c. to d.c. converter capable of producing from a relatively low voltage supply a relatively high output voltage for application to the spark plug to sustain a spark established by the spark plug generating means after the spark initiating pulse therefrom is no longer capable of maintaining the spark, said converter comprising: a) a step up transformer having primary and secondary windings; b) semiconductor switching means coupled to said primary winding to produce therein an oscillatory current flow, whereby to induce an oscillatory voltage in said secondary winding; c) voltage multiplier and rectifier means coupled to said secondary winding and including an output capacitor across which a rectified multiple of said secondary winding voltage is developed in use thereof, and d) circuit element means defining a resistance path in parallel with said capacitor to allow it to discharge when the circuit is inoperative.

Claim 30

Apparatus for producing spark ignition of an internal combustion engine wherein combustion is effected by means of a spark plug in a combustion chamber of the engine, comprising: spark pulse generating means for applying repetitively to the spark plug an electrical pulse capable of initiating a spark across the spark plug and a d.c. to d.c. converter capable of producing from a relatively low voltage supply a relatively high output voltage for application to the spark plug to sustain a spark established by the spark plug generating means after the spark initiating pulse therefrom is no longer capable of maintaining the spark, said converter comprising: a) a step up transformer having primary and secondary windings; b) semiconductor switching means coupled to said primary winding to produce therein an oscillatory current flow, whereby to induce an oscillatory voltage in said secondary winding; c) voltage multiplier and rectifier means coupled to said secondary winding and including an output capacitor across which a rectified multiple of said secondary winding voltage is developed in use thereof, and d) circuit element means defining a resistance path in parallel with said capacitor to allow it to discharge when the circuit is inoperative.

Claim 31

2 4. An internal combustion engine including: a) means defining a combustion chamber, ' b) a single spark plug·arranged to produce spark ignition in said combustion chamber, c) fuel injection means for injecting fuel into said combustion chamber in such a manner as to establish a stratified charge of fuel in the chamber with a higher fuel concentration in a region adjacent the spark plug than in regions remote therefrom, d) spark pulse generating means for applying to the spark plug an electrical pulse capable of initiating a spark across the spark plug, and e) generator means arranged to produce a voltage for application to the spark plug so as to sustain the spark established by said pulse generating means after said pulse generating means is no longer capable of maintaining the spark.

Claim 32

2 4. An internal combustion engine including: a) means defining a combustion chamber, ' b) a single spark plug·arranged to produce spark ignition in said combustion chamber, c) fuel injection means for injecting fuel into said combustion chamber in such a manner as to establish a stratified charge of fuel in the chamber with a higher fuel concentration in a region adjacent the spark plug than in regions remote therefrom, d) spark pulse generating means for applying to the spark plug an electrical pulse capable of initiating a spark across the spark plug, and e) generator means arranged to produce a voltage for application to the spark plug so as to sustain the spark established by said pulse generating means after said pulse generating means is no longer capable of maintaining the spark.

Claim 33

An internal combustion engine according to claim 24 including a piston and cylinder assembly and a cylinder head, the cylinder head including an aperture which receives the spark plug, and an aperture which receives said fuel injection means, and said piston having a head that includes a central dished portion to define said combustion chamber.

Claim 34

An internal combustion engine as claimed in claim 25 including inlet and outlet valves mounted on said cylinder head, and an inlet manifold coupled to said inlet valve and arranged to produce within the cylinder a swirling motion of gas generally coaxial with the cylinder bore.

Claim 35

An internal combustion engine as claimed in claim 26 including an exhaust gas recirculation system coupled to said outlet and inlet valves.

Claim 36

An internal combustion engine as claimed in claim 27 wherein said generator means comprises a d.c. to d.c. converter for developing said sustaining voltage from a low voltage supply.

Claim 37

2 9 . An internal combustion engine as claimed in claim 28 wherein said converter comprises: a) a step up transformer having a primary a secondary and a feedback winding, and a saturable core; b) semiconductor switching means coupled to said primary winding and to said feedback winding so as to define an oscillator to produce an oscillatory current flow in said primary winding that saturates said core with magnetic flux whereby to induce an oscillatory stepped up voltage in said transformer secondary winding; c) rectifying means coupled to said transformer secondary winding and arranged to produce a rectified output voltage for application to the spark plug, and d) the converter being so arranged that in the event said output voltage is shorted to earth the oscillator becomes damped and ceases operation.

Claim 38

An internal combustion engine as claimed in claim 24 including a dynamo electric machine driven by the engine and arranged to power said spark pulse generating means, and wherein said generator means comprises means arranged to derive from said dynamo electric machine an output for application to the spark plug so as to sustain sparks initiated thereby as aforesaid.

Claim 39

An internal combustion engine as claimed in claim 30 wherein said generator means includes a step up transformer coupled to said dynamo electric machine, and a rectifier connected to the transformer.

Claim 40

3 2. An internal combustion engine as claimed in claim 2 1 1 including sensor means for sensing at least one operating parameter of the engine, and means arranged to control the voltage level produced by said generator means in response to said sensor means.

Claim 41

An internal combustion engine as claimed in claim 31 wherein said dynamo electric machine comprises an alternator.

Claim 42

An internal combustion engine including: a) a piston and cylinder assembly defining a combustion chamber; b) a single spark plug arranged to produce spark ignition in said combustion chamber; c) chamber inlet and outlet means to allow inlet and exhaust gases to enter and leave the chamber respectively; d) exhaust gas recirculation means to recirculate exhaust gas from said outlet means to said inlet means; e) spark pulse generating means for applying repetitively an electrical pulse to the spark plug, said pulse being capable of initiating an electrical spark across the spark plug; f) generator means capable of producing a continuous output voltage for application to the spark plug so as to sustain the spark established by the spark pulse generating means after the spark initiated thereby is no longer capable of maintaining the spark.

Claim 43

An internal combustion engine including: a) a piston and cylinder assembly defining a combustion chamber; b) a single spark plug arranged to produce spark ignition in said combustion chamber; c) chamber inlet and outlet means to allow inlet and exhaust gases to enter and leave the chamber respectively; d) exhaust gas recirculation means to recirculate exhaust gas from said outlet means to said inlet means; e) spark pulse generating means for applying repetitively an electrical pulse to the spark plug, said pulse being capable of initiating an electrical spark across the spark plug; f) generator means capable of producing a continuous output voltage for application to the spark plug so as to sustain the spark established by the spark pulse generating means after the spark initiated thereby is no longer capable of maintaining the spark.

Claim 44

35 . An internal combustion engine as claimed in claim 34 wherein said generator means comprises a d.c. to d.c. converter including: a) a step up transformer having a primary a secondary and a feedback winding, and a saturable core; b) semiconductor switching means coupled to said primary winding and to said feedback winding so as to define an oscillator to produce an oscillatory current flow in said primary winding that saturates said core with magnetic flux whereby to induce an oscillatory stepped up voltage in said transformer secondary winding; c) rectifying means coupled to said transformer secondary winding and arranged to produce a rectified output voltage for application to the spark plug; and d ) the converter being so arranged that in the event said output voltage is shorted to earth the oscillator becomes damped and ceases operation.

Claim 45

An internal combustion engine including: a) a combustion chamber; b) a spark plug for producing spark ignition in said chamber; c) spark pulse generating means for applying repetitively to the spark plug an electrical pulse capable of initiating an electrical spark across the spark plug; d) an alternator driven by the engine and arranged to power said spark pulse generating means; e) means for deriving from said alternator an output voltage for application to the spark plug so as to sustain the spark established by the spark pulse generating means after the pulse generated thereby is no longer capable of maintaining the spark.

Claim 46

An internal combustion engine including: a) a combustion chamber; b) a spark plug for producing spark ignition in said chamber; c) spark pulse generating means for applying repetitively to the spark plug an electrical pulse capable of initiating an electrical spark across the spark plug; d) an alternator driven by the engine and arranged to power said spark pulse generating means; e) means for deriving from said alternator an output voltage for application to the spark plug so as to sustain the spark established by the spark pulse generating means after the pulse generated thereby is no longer capable of maintaining the spark.

Claim 47

An internal combustion engine as claimed in claim 36 wherein said means e) includes a transformer coupled to said alternator and a rectifier coupled to the transformer.